The applicator sets used most often are in the form of a fountain pen; they include a reservoir containing mascara made in liquid or paste form and a removable cap for closing the reservoir, comprising a sleeve or handle for a brush carried at the end of a rod joined to the cap. In the closed position of the applicator set, the rod and brush plunge into the reservoir. When the rod is withdrawn from the reservoir, a certain quantity of mascara is picked up on the brush and can be applied to the eyelashes. Moreover, the brush generally penetrates to the interior of the reservoir via a substantially circular opening bordered by a flexible lip, the role of which is to exert a wringing or squeegee action on the bristles of the brush and eliminate the excess makeup product picked up by the brush from the inside of the reservoir. In these applicators, the quantity of mascara picked up with the aid of a brush is always approximately the same, and the user cannot vary quantity to suit the user.
Applicator sets for eyelash makeup are also known including mascara in the form of a cake, or in other words in solid form, and a brush disposed in a case. To pick up the mascara, the user moistens the brush or possibly the cake with the aid of a liquid from a source outside the set, most often saliva, and rubs the brush over the cake of mascara to pick up more or less mascara as needed. The user is thus able to vary the amount of product on the brush arbitrarily, which is advantageous for eyelash makeup, especially because the eyelashes can be coated without clumping together. However, it is disagreeable for the user to put saliva on the brush or onto the cake of mascara, or to find some outside source of liquid. Moreover, the brushes used are typically flat brushes planted with tufts of bristles, which eventually become clogged, and with which the eyelashes cannot be curled by a flick of the wrist, as can be done with cylindrical brushes in applicator sets containing a reservoir of liquid mascara. Moreover, the bulk of the case, which is generally rectangular in shape, is a handicap when it is carried in the user's handbag.